Had a great chance to visit Heidelberg, although Heidelberg is small city & famous for its romantic view, castle and Altstadt. Heidelberg is young and lively city as it’s a university city. The most popular thing to do here is to visit old town, famous bridge on Neckar river, the castle and the old the holyspirit church for the city view. I believe the autumn season is the best season for Heidelberg when the whole city is surrounded with yellow green red season color and rush is comparatively less.